Grid controlled tubes



June 3, 195s T, w, SMALL ET AL 2,837,672-

GRID CONTROLLED `TUBES Filed June 15, 1953 HTTQNEY United States Patent 2,s37,672 GRID CoNrRoLLED TUBES Theodore W. Small, Phoenixville, and William P. Cole,

Quakertown, Pa., assignors to Philco Corporation, Philadelphia, Pa., a corporation of Pennsylvania Application .lune 15, 1953, Serial No. 361,738

Claims. (Cl. S13- 6) This invention relates .to grid-controlled tubes and more fespecially it relates to tubes of the type having at least one internal electrode which is obscured by another surrounding electrode.

A principal object of the invention 1s to provide a novel Ielectrode structure for electron tubes whereby the parts of the electrode assembly can be more accurately and expeditiously examined and adjusted.

Another object is to provide an improved electron tube of the type having at least one internal electrode with a surrounding or enclosing electrode, whereby the interior electrode can be visually checked for alignment after the .said surrounding electrode has been mounted in place.

A further object is to provide a novel electrode mount for tubes ofthe plural grid type.

A feature of the invention relates to a novel plate con- :struction for electron tubes wherein one section of the 'plate is irmly anchored in the tube mount while permit- :ting an integral adjacent section of the plate to be hinged outwardly for exposing theinner construction or align- @ment of the remaining electrodes of lthe mount.

A further feature relates to an improved manner of :anchoring the plate electrode of an electron tube.

A still further feature relates to the novel organization,

arrangement, and relative interconnection of parts which -cooperate to provide an improved tube of the so-called beam power type.

Other features and advantages not particularly dc- 1scribed will be apparent from a consideration of the en- :suing descriptions yand the appended claims.

In the drawing, which shows by way of example one preferred embodiment,

Fig. 1 is a vertical and partly sectional View of a tube according to the invention;

Figs. 2 and 3 are respective sectional views of Fig. l vtaken respectively along the lines 2 2 and 3 3 thereof;

Fig. 4 is a perspectiveview of one of the plate electrodes of Figs. 1 to 4;

Fig. 5 is a detailed, partly broken away View showing sthe aligned grid laterals of the grid electrodes of Figs. .1 to 3, and f Fig. 6 is a magnied View of a portion of Fig. 4.

While the invention finds its primary utility in connec- 'tion with electron tubes of the so-called beam power atype, it willy be understood that in certain of its aspects :the invention is not limited to such tubes, but is equally 'well useful in any kind of tube wherein the plate or anode electrode normally blocks visual inspection of one or more interior electrodes. Merely for explanatory purposes, therefore, the invention is illustrated as embodied in a dual pentode or dual beam power tube.

As shown in the drawing, the tube comprises the usual evacuating enclosing bulb or envelope 10 of any desired shape which hasl sealed therein the usual header 11, and through which header are sealed in a vacuumtight manner lthe various lead-in wires or contact prongs 12. Supported from the header 11 in any well known manner is an electrode assembly or mount which is preft ice erably of the so-ealled unitary type, wherein all the electrodes are assembled and held in place between a lower insulator disc 13 and an upper insulator disc 14, both of which discs may, for example, be of mica. These micas may have small radially extending teeth or extensions 15 for flexibly engaging the inner wall of bulb 1@ to support the mount against vertical swaying or tilting.

Anchored in any well known manner between the micas 13 and 14 are two electron emitting cathodes 16, 17, preferably, although not necessarily, of the indirectly heated type each having a tubular metal sleeve coated externally with any well` known electron emissive material, and having interiorly thereof a heater element or wire which is electrically insulated from the sleeve. While the drawing shows the cathodes 16 and 17 of cylindrically circular cross section, it will be understood that, if desired, they may be in the form of flattened tubes so that each cathode presents on opposite sides thereof substantially flat electron emissive surfaces. Also anchored between the micas are the metal uprights or grid side rod supports S19-20, 21-22. Wound around the side rods 19-20 is a iirst ine wire grid 23; likewise, wound around the side rods 2li- 22 is another grid 24. Likewise anchored between the micas are additional metal uprights or grid side rod supports 25--26, 27-25 Wound around the side rods 25-26 is a tine wire grid 29 similar to grid 23, and wound around the side rods 2'7-25 is a fine wire grid 30 similar to grid 24. In accordance with standard grid electrode manufacturing processes the line wire turns of each grid are rigidly attached in any well known manner to the respective side rods, thus holding the individual turns or grid laterals of eac'h grid in accurate parallel spaced relation.

Preferably, although not necessarily, the turns are 4formed or wound on a mandrel so that the grid laterals on opposite sides of the grid are substantially straight and parallel to each other. The grids are assembled between the micas so that the grid laterals of each inner grid, for example grid 23, are in planar alignment with the corresponding grid laterals of this outer grid, for example grid 29. Likewise, the grid laterals of grid 24 are in planar parallel alignment with the corresponding grid laterals of grid 30. Preferably also the grids are mounted so that the various side rods are all in substantially co-planar array. In accordance with the well known operation of beam power tubes, the side rods act somewhat as focusing devices so as to focus the electrons from the cathode into oppositely directed fan shaped beams represented by the dotted lines in Fig. 3.

Also anchored between the micas 13 and 14 are a pair of diametrically opposite metal uprights or rods 31, 32 which serve as the iinal anchoring posts for the plate electrodes, one of which is shown in perspective detail in Fig. 4, and which will be described in detail hereinbelow. For the purpose of setting up a desired electrostatic back or secondary emission retarding eld between the grids 29, 30 and their respective plate electrodes and disposed on opposite sides of the cathodes and grids are two T-shaped metal electrodes 33, 34. Each of these electrodes has a pair of rectangular windows 35, 36, 37, y

38 therein whose length corresponds to the length of the cathodes and whose width corresponds to the width of the fan shaped electron beams' from the cathode at the plane where the said windows are located. The upper and lower edges of the T-shaped electrodes 33, 34 are provided with integral tabs .S9-44 which fit within corresponding slits in the upper Iand lower micas and these tabs can be bent over at an angle, thus firmly anchoring the said electrodes 33 and 34 in pla-ce, with the windows 35-33 in planar parallelism with the grid laterals and in parallelism with the flat sections 45, i6 of plate 47 and with the flat sections 4S, d? of the plate 50.

La As shown more clearly in Fig. 4, each of these plate electrodes, for example plate 47, comprises the parallel, substantially llat sections d5, 46 which terminate in flat llanges l, These flanges are bent preferably at less than right angles, the ll-apnges 5l and 52 and the plate sections 45 and d6 forming a rigid unit. ln other words,

the said anges are pre-bent and maintain their bent relation with respect to the plate sections 45 and 4o. The construction of the plate electro-de Sti is identical with electrode lii. The upper and lower edges of thc liange 5l of plate d'7 have integral `anchoring tabs 15, 54 which are extended through corresponding slits in the upper and lower micas 13 and i4. Likewise, the flat section 45 of plate 4'/ at its upper and lower edges has integral anchoring tabs 5S, 56 which pass through corresponding slits in the upper and lower micas so as to preserve the pre-bent relation between the llange 5l and the flat plate section 45. Similarly, the tlange S7 of plate S@ has at its upper and lower edges similar integral anchoring tabs which pass through corresponding slits in the upper and lower micas. Likewise, the dat section #i9 of plate 55"@ has at its upper and lower edges integral anchoring tabs which pass through corresponding slits in the upper and lower micas.

Flhe dat sections, for example sections 45 and 46 of plate electrode 47, are joined by a somewhat curved section SS. Likewise, the flat sections t3 and 49 of plate 59 are joined by 'a similar curved section 59. The plate Sn has, of course, a bent-back ilange titl similar to the flange 52 of plate 47. The lianges 52 and 6@ are provided with longitudinally extending embossed ribs 61, 62, which are adapted to receive the respective support rods 3l, 32 to be welded thereto when the tube is finally checked for electrode alignment which will be described hereinbelow. Preferably the sections 45, 46 Iand 53 of plate electrode 47 and the corresponding section d, 49 and 59 of electrode 59 have a series of embossed ribs 63 for strengthening each plate in the direction of these ribs.

In accordance with one feature of the invention, the bent portion between sections 45 and 5S of plate 47, and the corresponding bent portion between the sections 49 and 59 of plate 5@ are provided with slits' 64 located between the adjacent ribs 63. Fig. 6 shows in greatly magnified perspective View a section of these bent or corner portions to show the slits 64. However, the remaining c-orner portion between the sections d6 and S3 of plate 47 and the corner portion between the sections 43 and 59 of plate Si) are unslitted. slitting of each plate electrode it is possible to hinge the sections 58 and 52 of plate 4,7 as a unit around the slitted corner as 'a hinge. This relation is shown in the dotted line positions in Fig. 3. During this hinging or opening movement of the plate sections the remaining sections S7 and 49 of plate 50 remain in their fixed position by reason of the engagement between the anchoring tabs 53, 5d, 5S, 56 with their respective micas. Likewise, the sections 53, 46 and S2 of plate 47 can be hinged to an open position without distorting the anchored relation of the remaining sections t5 and 5l of plate 47.

ln beam power tubes it is highly important that before the bulb portion lll is sealed to the header 11 that it would be possible to examine whether the various interior electrodes, especially the grid electrodes, are properly positioned with their grid later-als in planar alignment and with their supporting side rods in proper parallelism. In the ordinary construction of such tubes the plate electrode completely encloses the remaining electrodes, and it is not possible to check the alignment of the grid l'aterals once the plate electrode has been assembled in the mount.

With the contruction according to the invention all the electrodes can be assembled in the mount but the ilanges 52 and 6d of the plate electrodes 47 and lg are assembled in their full line position, as shown in Fig.

As a result of this y 3, but without welding the embossed ribs 61, 62 to the support rods 31, 32. Consequently, it is possible before assembling the bulb over the mount to hinge the movable sections of each plate outwardly, as represented by the dotted line positions in Fig. 3, so that it is possible to examine visually the alignment of the various electrodes, especially the grids, to etect any final adjustments that may be necessary. When the interior electrodes are thus properly aligned the movable hinged sections of each plate can be swung back to their full line positions, as seen in Fig. 3, whereupon the embossed ribs 6l, 62 can be welded to the respective support rods. lt will be understood, of course, that after the mount has been checked for cathode and grid alignment, and after the plate electrodes have been welded to their respective support rods 3l and 32., the `bulb lil is assembled over the mount and sealed to the header 11 in any well known manner, after which the tube can be evacuated and processed by any well known technique.

The foregoing described mount construction not only has the advantage of enabling the grid electrodes to be checked for proper alignment before sealing the bulb to the header but it also has the advantage that completed tubes can be opened for analysis and the condition of the interior electrodes can be checked without destroying their alignment. Hertofore with the conventional plate construction it has been necessary to cut away a portion of the plate electrode or otherwise to distort the mount to examine the internal electrodes. In accordance with the invention, if a tube is required to be checked for defects or other conditions, the glass bulb 10 can be broken away and then the plate support rods 31, 32 can be cut close to the top and bottom micas 13, 14, thus leaving the movable sections of the plate electrodes free to be swung outwardly for the examination of the internal electrodes. This enables the internal electrodes to be checked without any distortion thereof.

lt will be understood, of course, that while one particular manner of hinging the xed and swingable sections of each plate together has been described that any other hinging arrangement may be employed. Various changes and modications may be made in the disclosed embodiment without departing from the spirit and scope of the invention.

What is claimed is:

l. An electron tube mount having at least one electrode which is enclosed by another electrode and visually obscured by said other electrode, insulator spacer members at opposite ends of both electrodes, said spacers being joined by a plurality of metal rods and forming with said electrodes a unitary assembly, said other electrode having two opposite main walls which face the iirst mentioned electrode, said main walls being joined by an intervening yoke, said main walls and yoke obscuring the first mentioned electrode against visual examination when said other electrode is assembled in enclosing relation to said first electrode, each of said main walls terminating in a bent back wing, one of said main walls and its wing being provided at opposite ends with means permanently interlocking said one wall with said insulator spacers, maintaining said one main wall in fixed relation to the first mentioned electrode, the joint between said one main wall and said yoke being slitted to form a hinge around which said yoke and said other main wall with its wing can he swung as a unit outwardly to reveal the tirst electrode and can then be swung inwardly to bring both said main walls in predetermined symmetrical spaced relation on opposite sides of said lirst electrode, and means anchoring the wing of said other main wall to hold both said main walls in said symmetrical relation.

2. An electron tube mount according to claim 1, in which said first electrode is in the form of a wire wound grid which is anchored between said insulator spacers independently of the said other electrode.

3. An electron tube mount according to claim 1, n which said wing of said other main wall is Welded vto one of said metal rods and maintains said symmetrical relation of said main walls when said yoke and other main wall are swung as a unit into enclosing relation around the rst mentioned electrode. v

4. An electron tube mount according to claim 1, in which the said joint between said one main wall and said yoke is provided with a plurality of aligned struck out tongues which dene a corresponding plurality of aligned hinge sections.

5. An electron tube mount according to claim 1, in which a plurality of said other electrodes each of similar construction are provided and each enclosing a correspending wire wound grid, said plurality of other electrodes when swung into said symmetrical spaced relation to their respective grid electrodes defining a substantially complete tubular electrode chamber within each half of which the corresponding wire wound grid is symmetrically located.

References Cited in the tile of this patent UNITED STATES PATENTS 

